Technology, economics may counter climate impact

February 24, 2011
By Krishna Ramanujan

Geographic range of maize production in Middle China, including Shandong, Hebei, Henan, Shanxi and Shaanxi provinces analyzed in the study.

The impacts of climate change on corn yields in the United States and China in coming decades may not be all bad, according to a new Cornell and University of Tokyo study published in a recent issue of the journal Agricultural Systems.

Most studies looking at the impacts of climate change on agriculture use computer models based on climatic, soils and cultivar variables, but the model used in this study also incorporates future technological advancements and economic considerations.

With this more complete picture, the researchers found that by 2030, maize yields may not decline as much as climate-only models predict, and that yields may increase greatly in some scenarios in both China and the United States.

"The impacts of climate change are not going to uniformly be the same everywhere, there will be winners and losers," said Harry Kaiser, Cornell professor of applied economics and management and one of the paper's co-authors.

For example, warm weather continents like Africa and South America could bear more negative impacts from climate changes this century if temperatures rise and precipitation declines, while Canada stands to gain from warming temperatures, Kaiser said. "But if we knock down trade barriers, losses may offset gains elsewhere through trade," he added.

Geographic range of maize production in Midwestern United States, including Iowa, Illinois, Ohio, Indiana, Nebraska, South Dakota, Wisconsin and Minnesota states analyzed in the study.

With China and the United States accounting for 50 percent of the world's maize production, the researchers focused their study on key growing areas in eight midwestern U.S. states and five Middle China provinces. Also, climate models predict temperature more accurately than precipitation shifts. For this reason, the researchers examined scenarios that included extreme precipitation increases and decreases for each location.

The computer model used in the study included climate, soil, cultivar, technological and economic variables. Technological variables accounted for such factors as research to develop new cultivars with higher yields that are more tolerant to stressors like drought, and new varieties that might be better suited to a longer growing season, an expected outcome in North America in coming decades.

Using an extreme scenario with a global temperature rise of 1.46 degrees Celsius (2.6 Fahrenheit) from 2000 levels, the model predicted that by 2030:

In Middle China, if precipitation increases by 30 percent, maize yields would increase by 23 percent, but if precipitation decreases by 30 percent, maize yields only increase by 11 percent. In the summer in this part of China, higher temperatures can increase evaporation rates, making maize yields sensitive to water deficiency.

In the U.S. Midwest, if precipitation increases by 30 percent, maize yields would drop by 7 percent, but if precipitation declines by 30 percent, maize yields could increase by 42 percent. That's because the Midwestern states studied already receive adequate rainfall and more rain is likely to waterlog roots.

Still, the researchers argue that a decrease in maize yields would lead to increased maize prices, which in turn would induce farmers to add more investments in production inputs to raise yields.

"The decrease in actual yields may not be as dramatic as predicted in cases where only climate factors are considered," Kaiser said.

Xiang Li, a researcher at the University of Tokyo, is the paper's lead author.

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3 comments

lol, someone rated this story 1/5. The warmers just hate good news. I wonder what it would look like if they did the same kind of study for other important food crops like soy. I further wonder what it looks like if you include the option for farmers to change crop mixes to different crops. An area too wet for corn may become good for something else, for example. I wonder if they even accounted for different kinds of corn, such as animal feed corn versus alcohol corn, and how changes in climate could allow changes in types of corn in different places? I have heard that most corn in the US is not the type you eat anyway. My Uncle once said to me, about all the corn in Missouri, "corn, corn, corn as far as the eye can see, and not a bite to eat".

Well of course it is. Nobody seriously doubts that temperatures have risen over the past few decades. I think that's a given.

It does however do a good job of pointing out and quantifying some of the pieces that climate models may be missing in regard to predicting the effects of warming, and they are claiming that we may not all die in 100 years after all. It's still based on a computer model though and as I was suggesting, it may not be as comprehensive as it could be. The only reason I really said anything is because somebody rated the article 1/5, and I can't really understand why.

The study assums a temp increase and attempts to estimate the effects of the assumed increase. That sounds like an interesting thing to do. I like this study. I'm not sure how important or accurate it can be, but the concept is a good one for future discussions.

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